Twenty-five percent of all dog bone cancers occur in the radius and ulna, the bones of the lower forelimb. Most of these are osteosarcomas, an aggressive malignant type of bone tumor which will spread rapidly to other areas of the body.
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Signs
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Your dog will be lame with weaker leg muscles on the side of the tumor and there will be a firm swelling under the skin, most commonly towards the paw. Large breed dogs around 7 to 8 years old are most commonly affected and may have had a trauma to the site.
Diagnosis
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Your veterinarian will take X-rays to confirm that there is a tumor present and then possibly take a small sample of the lump so that the lab can determine which particular type of bone cancer it is. The vet may also X-ray your dog's chest to see if there is visible spread of the cancer to the lungs. By the time that diagnosis is reached the cancer has usually already spread around the body.
Treatment
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Due to the pain and weakening of the bone caused by the tumor, most treatment regimes begin with its removal. Amputation of the limb is the more common method but a technique called limb sparing in which metal plates and bone grafts are used to fill the hole and provide strength to the limb can be used. Both methods may be followed by chemotherapy.
Biological therapies which enhance the immune system's ability to fight the tumor are available.
All dogs require medication for pain relief and radiotherapy can be used to further ease painful tumors when surgery is not an option.
Follow-up
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X-rays and scans done every three months can be used to assess the rate of spread of the cancer and to adjust chemotherapy treatments. Due to the aggressive nature of the cancer many owners do not opt for follow-up tests, but the information gained helps develop new treatments for future cases.
Survival
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With surgery alone the average survival time from diagnosis is 23 weeks but this increases to an average of one year if chemotherapy is also used. Biological therapies give an average survival time of 31 weeks.
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